2D Inverse Kinematics

jersmi's picture

Seeking advice / thoughts on inverse kinematics and what is possible / practical in QC at present.

Specifically I want a tracking point (or rollovers triggering movement) to be the "shoulder" joint, with sprites as upper arm, forearm and hand. As tracking point moves, arm "contraptions" move around in interesting ways.

Seems doable in a simplified way. Any thoughts using 3D transforms, some trig, iterated sprites, etc.? I have not dug into this at all yet. Presenting it and talking through it helps, and I know folks have done similar things. Actually, this concept applies to other scenarios, too -- l-systems, growing iterations, organic structures, etc.

Looking at this kineme post, focused on 3D models: http://kineme.net/FeatureRequests/SkeletalanimationInverseKinematics

And some math here: http://www.learnaboutrobots.com/inverseKinematics.htm

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dust's picture
Re: 2D Inverse Kinematics

well you can try using clamping and directional springs to achieve some sort of inverse kinematics in 2d i guess ? i would say inverse kinematics would inherently be a 3d type of thing. i use ik's all the time in combination with constraints to get around the gimbal lock issue. i also use fk's a bunch in unity, maya, cheetah etc..

thats easy to say i use them but implementing them in qc is another thing entirely. im just waiting for full collada imports etc.. in hopes that ik chains will be available shortly. that is to not say that someone couldn't pull it off right now in qc. try using a chain of springs with a feedback patch.

it would be sort of like you have 3 objects 1, 2 and 3. attach object 1 to object 2 with a spring then attach object 2 to object 3 with clamping spring. the attach object 1 to object 3 with a directional spring and then move object 1 around with interactions to see if you get the desired effect or any other combination then report back your findings.

there is a spring example in /sys/lib/graphics/patches "clamping springs"

jersmi's picture
Re: 2D Inverse Kinematics

Okay, thanks for the lead on the springs patches and comps -- I can see how that's a good place to start. Yeah, I know the IK stuff is robotics, 3D, etc., but I didn't know what to call it -- chain reaction stuff, moving one thing makes the rest move with it, like parented objects in 3D, After Effects, etc. but with more physics / expression, like IK.